I've read a few different pieces recapping today. (None of them quite match the description weighing in here but none the less). It appeared to me at least from what I read, SCOUTS biggest concern to be one state having such a major impact on what other states can do with their elections. If they ruled in favor of Colorado, that pretty much makes it law of the land. If they rule against Colorado, that sets a precedent should there be future incidents.
Not anything I'm real confident in but I got the feeling of a punt, SCOTUS won't want to rule against State Sovereignty, and siding with state sovereignty is the easiest way for them to avoid one state's case deciding, in either direction, for the other 49 states in the nation. Just a hunch, way open to be wrong.
PS-Section 3 is not exclusive to physically committing insurrection (if you believe his actions were not that of insurrection). There are other elements that disqualify under section 3.